Wheels are important safety parts of an automobile driving system, and the requirement for the mechanical properties of the material thereof is usually strict. In addition, the weight reduction of the automotive industry requires the more use of aluminum alloy as a substitute of steel in the materials for wheels. The mainstream manufacturing processes for aluminum wheels include a low-pressure casting process for cast aluminum alloy wheels and a forging process for wrought aluminum alloy wheels.
The low-pressure casting indicates that molten aluminum alloy in a holding furnace is pressed into a mold cavity through dry compressed air, and then the molten aluminum alloy is transformed into a casting by creating a sequential solidification condition under certain pressure. Its characteristic is that the holding pressure is generally not more than a standard atmospheric pressure, whereas the yield strength of the spokes of the cast aluminum wheel is usually about 200 MPa and the elongation is 7%.
The forging indicates that wrought aluminum alloy bars are subjected to a solid-state forming technology of forging, spinning or the like, and it has the characteristics that the press tonnage and the equipment investment are high, the mechanical properties of the material for the forged aluminum wheel are more excellent, the yield strength of the spokes of the forged aluminum wheel is usually about 300 MPa and the elongation is 10%.